Circuit and method for recovering clock data in highly integrated semiconductor memory apparatus

ABSTRACT

Circuit and method for recovering clock data in highly integrated semiconductor memory apparatus includes a plurality of signal receiving units configured to receive signals through a plurality of input/output pads and transfer the signals according to a receiving reference clock, the signal receiving units being divided into groups, a plurality of phase detection units configured to detect phases of signals output from the groups of the signal receiving units, a plurality of phase detection control units configured to control the phase detection units so that the phase detection units sequentially detect the phases of the signals output from each of the groups of the signal receiving units and a notification unit configured to output signals output from the phase detection units.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority of Korean patent applicationnumber 10-2007-0111482, filed on Nov. 2, 2007, which is incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a highly integrated semiconductordevice, and more particularly, to a semiconductor memory deviceincluding a clock data recovery (CDR) circuit for recovering signals anddata distorted during high-speed processing.

Semiconductor memory devices are used for storing data in varioussystems such as a system composed of a plurality of semiconductordevices. When a data processing device, such as a central processingunit (CPU), requests or sends data, a semiconductor memory deviceoutputs or stores the data based on address information received fromthe data processing device.

As the operating speed of a semiconductor device system increases owingto the advance of semiconductor integrated circuit technology, thesemiconductor device system requires high-speed semiconductor memorydevices capable of rapidly outputting and storing data. For high-speedand stable operations of a semiconductor memory device, circuits of thesemiconductor memory device need to be operated at a high speed. Thatis, the circuits of the semiconductor memory device need to processsignals or data rapidly and transfer the signals or data at a highspeed.

As the operating speed of semiconductor memory devices need to be highfor being used in high-speed systems, the signal/data transmission speedof interfaces is also required to be high. A clock data recovery (CDR)method has been developed to prevent malfunctions or instable operationsof a semiconductor memory device caused by noises, interferences, anddistortions of signals and data.

That is, a recent semiconductor memory device includes a CDR circuit forreliably transferring signals and data at a high speed. CDR technologyis used in most high-speed systems for recovering original data andclock signals from data and clock signals distorted or changed duringtransmission.

In a semiconductor memory device, transmission of data and clock signalscan be delayed due to various reasons. In this case, the semiconductormemory device cannot normally operate according to the data and clocksignals, and thus the possibility of malfunction of the semiconductormemory device increases. To solve these problems, circuits of thesemiconductor memory device can be operated according to an inner clockproduced corresponding to an external reference clock. When the innerclock is not in phase with the external reference clock, the phasedifference is detected and reported to the circuits so as to allow thecircuits to change the phase of the inner clock in response to thereported phase difference or operate in consideration of the phasedifference.

The above-described operation can be performed using a CDR circuit. Forthis, the CDR circuit includes a phase comparator and a filter. Thephase comparator detects a difference between the external referenceclock and the inner clock, and the detection result is output throughthe filter.

FIG. 1 is a block diagram illustrating a conventional semiconductormemory device including CDR circuits.

Referring to FIG. 1, for example, the semiconductor memory deviceincludes first to thirty second data pads DQ0 to D31, and first tothirty second CDR circuits 120_0 to 120_31 respectively connected to thefirst to thirty second data pads DQ0 to D31. The first CDR circuit 120_0includes a receiver 122_0, a sampling unit 124_0, a delay unit 128_0,and a phase detection unit 126_0. The other CDR circuits 120_1 to 120_31have the same elements. Thus, descriptions of the other CDR circuits120_1 to 120_31 will be omitted.

Each of the first to thirty second CDR circuits 120_0 to 120_31connected to the first to thirty second data pads DQ0 to D31 can recoverclock data with no aid from other devices. This will now be describedusing the first CDR circuit 120_0 as an example. The receiver 122_0receives a signal through the first data pad DQ0 and transfers thesignal to the sampling unit 124_0. First, the sampling unit 124_0transfers the signal to the phase detection unit 126_0 according to areceiving reference clock RX_CLK. The phase detection unit 126_0 detectstransition time points of signals transferred from the sampling unit124_0 (that is, time points at which successively transferred signalschange from a logic high level to a logic low level, or from a logic lowlevel to a logic high level). Then, the phase detection unit 126_0calculates a delay value so as to place the transition time points onthe centers of rising and falling edges of the receiving reference clockRX_CLK. The delay unit 128_0 delays the receiving reference clock RX_CLKaccording to the delay value so as to adjust the phase of the receivingreference clock RX_CLK. Then, the sampling unit 1240 transfers signalstransferred from the receiver 1220 to an inner unit of the semiconductormemory device according to the phase-adjusted receiving reference clockRX_CLK. Since the phase of the receiving reference clock RX_CLK can beadjusted as described above, signal input/output errors can be preventedwhen the semiconductor memory device receives and transfers signals at ahigh speed.

Each of the first to thirty second CDR circuits 120_0 to 120_31connected to the first to thirty second data pads DQ0 to D31 includes aclock generator (not shown). The clock generator generates a receivingreference clock RX_CLK that is used for determining the time forrecognizing input signals.

Since the first to thirty second data pads DQ0 to D31 can have differentdata transmission delay levels, the first to thirty second CDR circuits120_0 to 120_31 are connected to the first to thirty second data padsDQ0 to D31, respectively. However, the first to thirty second CDRcircuits 120_0 to 120_31 occupy a large area of the semiconductor memorydevice. Therefore, the number of data transmission channels of thesemiconductor memory device may be limited, or the power consumption ofthe semiconductor memory device may be increased due to the CDRoperation.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to providing anapparatus and method for improving a clock data recover (CDR) circuit ofa highly integrated semiconductor memory apparatus so as to be usefullyused in a highly integrated semiconductor apparatus, an electronicdevice, and an electronic system, the apparatus and method beingconfigured to recover clock data using a small space and power bygrouping signal input/output pads and allowing each of the groups toshare a clock data recovery (CDR) circuit.

In accordance with an aspect of the present invention, there is provideda plurality of signal receiving units configured to receive signalsthrough a plurality of input/output pads and transfer the signalsaccording to a receiving reference clock, the signal receiving unitsbeing divided into groups, a plurality of phase detection unitsconfigured to detect phases of signals output from the groups of thesignal receiving units, a plurality of phase detection control unitsconfigured to control the phase detection units so that the phasedetection units sequentially detect the phases of the signals outputfrom each of the groups of the signal receiving units and a notificationunit configured to output signals output from the phase detection units.In accordance with another aspect of the present invention, there isprovided a semiconductor memory apparatus configured to detect phases ofparallel signals received according to a receiving reference clock andconvert the detection result into a serial signal; and a data processingapparatus configured to detect a signal transmission state using theserial signal received from the semiconductor memory apparatus andadjust output times of new signals to be transferred to thesemiconductor memory apparatus. In accordance with an aspect of thepresent invention, there is provided a method for recovering clock datathat includes a step of generating a first serial signal by combiningfirst signals received through even numbered input/output pads afterdetecting phases of the first signals, a step of generating a secondserial signal by combining second signals received through odd numberedinput/output pads after detecting phases of the second signals, a stepof transferring a serialized signal produced by combining the first andsecond serial signals and adjusting output times of new signals based ona signal transmission state detected using the serialized signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a conventional semiconductormemory device including clock data recovery (CDR) circuits.

FIG. 2A is a block diagram illustrating a semiconductor memory apparatusand a data processing apparatus in accordance with an embodiment of thepresent invention.

FIG. 2B is a flowchart for explaining operations of the semiconductormemory apparatus and the data processing apparatus of FIG. 2A, inaccordance with an embodiment of the present invention.

FIG. 3A is a block diagram illustrating a semiconductor memory apparatusand a data processing apparatus in accordance with another embodiment ofthe present invention.

FIG. 3B is a flowchart for explaining operations of the semiconductormemory apparatus and the data processing apparatus of FIG. 3A, inaccordance with an embodiment of the present invention.

FIG. 4 is a circuit diagram illustrating a phase detection control unitof the semiconductor memory apparatus of FIG. 3A, in accordance with anembodiment of the present invention.

FIG. 5 is a circuit diagram illustrating a serialization unit of thesemiconductor memory apparatus of FIG. 3A, in accordance with anembodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Hereinafter, circuit and method for recovering clock data in highlyintegrated semiconductor memory apparatus in accordance with the presentinvention will be described in detail with reference to the accompanyingdrawings.

FIG. 2A is a block diagram illustrating a semiconductor memory apparatusand a data processing apparatus in accordance with an embodiment of thepresent invention.

Referring to FIG. 2A, the semiconductor memory apparatus may be adynamic random access memory (DRAM). The semiconductor memory apparatusreceives a plurality of parallel signals according to a receivingreference clock signal and detects phases of the signals. Then, thesemiconductor memory apparatus converts the detection result into aserial signal. The data processing apparatus may be a general processingunit (GPU). The data processing apparatus detects a signal transmissionstate using the serial signal received from the semiconductor memoryapparatus. Then, the data processing apparatus controls output times ofnew signals to be transferred to the semiconductor memory apparatus. Thesemiconductor memory apparatus and the data processing apparatus canform a system capable of clock data recovery.

In the semiconductor memory device of FIG. 1, each of the CDR circuits120_0 to 120_31 connected to the data pads DQ0 to DQ31 can adjust areceiving time of input data. However, in the current embodiment shownin FIG. 2A, the semiconductor memory apparatus receives signals (ordata) and informs the data processing apparatus of a transmission stateof the signals, and then the data processing apparatus adjusts times fortransferring the next signals to the semiconductor memory apparatus.

In detail, referring to FIG. 2A, the semiconductor memory apparatusincludes first to thirty second signal phase detection units 220_0 to220_31 and a notification unit. The signal phase detection units 220_Uto 220_31 receive signals from the data processing apparatus throughfirst to thirty second input/output pads DQ0 to DQ31 and transfer thesignals. In addition, the signal phase detection units 220_0 to 220_31detect the phases of the received signals. The notification unittransfers output signals of the signal phase detection units 220_0 to220_31 to the data processing apparatus for informing the dataprocessing apparatus of a signal transmission state of the signals. Thenotification unit includes a serialization unit 280 and a transmissionunit 290. The serialization unit 280 serializes signals received fromthe signal phase detection units 220_0 to 220_31, and the serializedsignals are transferred to the data processing apparatus through thetransmission unit 290.

The first to thirty second signal phase detection units 220_0 to 220_31have the same structure. Thus, only the first signal phase detectionunit 220_0 will now be described, and descriptions of the second tothirty second signal phase detection units 220_1 to 220_31 will beomitted for conciseness. The first signal phase detection units 220_0include a receiver 222_0, a sampling unit 224_0, and a phase detectionunit 226_0. The receiver 222_0 receives signals input through the firstinput/output pad DQ0. The sampling unit 224_0 transfers the signalsreceived from the receiver 222_0 to the phase detection unit 226_0according to a receiving reference clock RX_CLK. The phase detectionunit 226_0 detects phases of the signals received from the sampling unit224_0.

In operation, the receiver 222_0 receives signals through the firstinput/output pad DQ0 and transfers the signals to the sampling unit224_0. The sampling unit 224_0 transfers the signals received from thereceiver 222_0 to the phase detection unit 226_0 according to areceiving reference clock RX_CLK. The phase detection unit 226_0 detectstransition time points of the signals received from the sampling unit224_0 (that is, time points at which successively transferred signalschange from a logic high level to a logic low level, or from a logic lowlevel to a logic high level). Then, the phase detection unit 226_0transfers the signals to the serialization unit 280. In this way,signals are transferred to the serialization unit 280 from the firstsignal phase detection unit 220_0 and the other second to thirty secondsignal phase detection units 220_1 to 220_31. Then, the serializationunit 280 serializes the signals and transfers the serialized signals tothe data processing apparatus through the transmission unit 290. Thedata processing apparatus detects a signal transmission state from theserialized signals received through the transmission unit 290. Then, thedata processing apparatus adjusts signal output times based on thedetected signal transmission state.

The data processing apparatus includes a receiving unit 540 and first tothirty second signal transmission determination units 520_0 to 520_31.The receiving unit 540 receives serialized signals transferred throughthe transmission unit 290. The signal transmission determination units520_0 to 520_31 analyze signals output from the receiving unit 540 fordetecting a signal transmission state and determining a delay valueaccording to the detection result. Each of the signal transmissiondetermination units 520_0 to 520_31 includes a delay unit and an outputunit Tx. The delay unit is configured to delay output of new signals,and the output unit Tx outputs delayed new signals under control of thedelay unit. That is, unlike a conventional semiconductor memory device,the data processing apparatus adjusts output times of new signalsaccording to serialized signals received from the semiconductor memoryapparatus so that high-speed signals and data transmission can bestabilized.

FIG. 2B is a flowchart for explaining operations of the semiconductormemory apparatus and the data processing apparatus of FIG. 2A, inaccordance with an embodiment of the present invention.

Referring to FIG. 2B, clock data can be recovered as follows. Inoperation 5202, the semiconductor memory apparatus detects phases ofinput signals. In operation 5203, the signals are combined. In operationS204, the combined signals are sent to the data processing apparatus. Inoperation S205, the data processing apparatus detects a signaltransmission state of the signal and decreases or increases a delayvalue for adjusting output times of new signals.

FIG. 3A is a block diagram illustrating a semiconductor memory apparatusand a data processing apparatus in accordance with another embodiment ofthe present invention.

Referring to FIG. 3A, the data processing apparatus has the samestructure as the data processing apparatus depicted in FIG. 2A. However,in the semiconductor memory apparatus of 3A, a plurality of phasedetection units 340_0 to 340_15 are shared by neighboring signal phasedetection units 320_0 to 320_31.

In detail, the semiconductor memory apparatus includes a plurality ofsignal receiving units 320_0 to 320_31, the plurality of phase detectionunits 340_to 340_15, a plurality of phase detection control units 360_0to 360_15, and a notification unit. The signal receiving units 320_0 to320_31 receive signals from the data processing apparatus through aplurality of input/output pads DQ0 to DQ31 and transfer the signalsaccording to a receiving reference clock RX_CLK. The signal receivingunits 320_0 to 320_31 are divided into groups. The phase detection units340_0 to 340_15 receive outputs of the groups of the signal receivingunits 320_0 to 320_31 for detecting phases of the outputs. The phasedetection control units 360_0 to 360_15 control the phase detectionunits 340_0 to 340_15 to sequentially detect the phases of the outputsof the groups of the signal receiving units 320_0 to 320_31. Thenotification unit transfers outputs of the phase detection units 340_0to 340_15 to the data processing apparatus so as to allow the dataprocessing apparatus to detect a signal transmission state. Thenotification unit includes a serialization unit 380 and a transmissionunit 390. The serialization unit 380 serializes signals received fromthe phase detection units 340_0 to 340_15, and the serialized signalsare transferred to the data processing apparatus through thetransmission unit 390.

The signal receiving units 320_0 to 320_31 have the same structure.Thus, only the first signal receiving unit 320_0 will now be described,and descriptions of the second to thirty second signal receiving units320_1 to 320_31 will be omitted. The first signal receiving unit 320_0includes a receiver 322_0 and a sampling unit 324_0. The receiver 322_0receives signals input through the first input/output pad DQ0. Thesampling unit 324_0 transfers signals according to a receiving referenceclock RX_CLK.

Signals input through the input/output pads DQ0 to DQ31 are recognizedand transferred by the plurality of signal receiving units 320_0 to320_31 corresponding to the input/output pads DQ0 to DQ31. Signalsoutput from the neighboring two of the signal receiving units 320_0 to320_31 are transferred to a corresponding one of the phase detectionunits 340_0 to 340_15 that are controlled by the phase detection controlunits 360_0 to 360_15. That is, two input/output pads share one phasedetection unit. The phase detection control units 360_0 to 360_15control the phase detection units 340_0 to 340_15 to detect the phasesof signals output from the even or odd numbered signal receiving units320_0 to 320_31. Therefore, in accordance with the current embodiment,the semiconductor memory apparatus can have a reduced CDR circuit areaas compared with the semiconductor memory apparatus of FIG. 2A.

FIG. 3B is a flowchart for explaining operations of the semiconductormemory apparatus and the data processing apparatus of FIG. 3A, inaccordance with an embodiment of the present invention.

Referring to FIG. 3B, clock data can be recovered as follows. Inoperation S302, the semiconductor memory apparatus detects the phases ofsignals input through even numbered input/output pads. In operationS303, the signals input through the even numbered input/output pads arecombined. In operation S304, the semiconductor memory apparatus detectsthe phases of signals input through odd numbered input/output pads. Inoperation 5305, the signals input through the odd numbered input/outputpads are combined. In operation S306, the signals combined in operationsS303 and S305 are serialized and transferred to the data processingapparatus. In operation 5307, the data processing apparatus detects asignal transmission state and decreases or increases a delay value forcontrolling output times of new signals.

FIG. 4 is a circuit diagram illustrating the phase detection controlunit 360_0 of FIG. 3A, in accordance with an embodiment of the presentinvention. The phase detection control units 360_0 to 360_15 of thesemiconductor memory apparatus of FIG. 3A have the same structure. Thus,only the first phase detection control unit 360_0 will now be described.

Referring to FIG. 4, the phase detection control unit 360_0 includes aflip-flop 362_0 and an inverter 364_0. The flip-flop 362_0 receives asignal and outputs the signal according to a first clock CLK/N producedby dividing a system clock by a predetermined value. The inverter 364_0inverts the signal output from the flip-flop 362_0 and returns theinverted signal to an input of the flip-flop 362_0 to generate a pulsesignal having a width corresponding to a rising edge of the first clockCLK/N for controlling the phase detection unit 340_0. The phasedetection unit 340_0 detects the phase of a signal output from the firstsignal receiving unit 320_0 or the second signal receiving unit 320_1and sends the signal to the serialization unit 380. In FIG. 4, N is anatural number selected for recognizing signals output from twoinput/output pads.

FIG. 5 is a circuit diagram illustrating the serialization unit 380 ofFIG. 3A, in accordance with an embodiment of the present invention.

Referring to FIG. 5, the serialization unit 380 includes a plurality offlip-flops 382_0 to 382_7, 384_0 to 384_7, 386_0, and 3861, and aplurality of multiplexers 383_0 to 383_7, 385_0, 385_1, and 387. Theflip-flops 382_0 to 382_7, 384_0 to 384_7, 386_0, and 386_1 receivesignals from the phase detection units 340_0 to 340_15 and transfer thesignals according to division clocks produced by dividing a referenceclock by a predetermined value. The multiplexers 383_0 to 383_7, 385_0,385_1, and 387 receive signals output from the flip-flops 382_0 to382_7, 384_0 to 384_7, 386_0, and 386_1 and transfer the signalssequentially.

In detail, the flip-flops 382_0 to 382_7, 384_0 to 384_7, 386_0, and386_1 of the serialization unit 380 can be grouped into first flip-flops382_0 to 382_7, second flip-flops 384_0 to 384_7, and third flip-flops386_0 and 386_1. The multiplexers 383_0 to 383_7, 385_0, 385_1, and 387of the serialization unit 380 can be grouped into first multiplexers383_0 to 383_7, second multiplexers 385_0 and 385_1, and a thirdmultiplexer 387. The first flip-flops 382_0 to 382_7 receive data frominput/output pads DQ0 to DQ3, DQ4 to DQ7, . . . , and DQ28 to DQ31,respectively, and transfer the signals according to a first divisionclock CLK/32 produced by dividing a system clock by 32. The firstmultiplexers 383_0 to 383_7 receive signals from the first flip-flops382_0 to 382_7 and output the signals sequentially. Here, each of thefirst multiplexers 383_U to 33_7 receive four signals from each of thefirst flip-flops 382_U to 382_7. The second flip-flops 384_U to 384_7receive signals output from the first multiplexers 383_0 to 383_7 andtransfer the signals according to a second division clock CLK/8 producedby dividing the system clock by 8. The second multiplexers 385_0 and3851 receive signals output from the second flip-flops 384_0 to 384_7and output the signals sequentially. Here, each of the secondmultiplexers 385_0 and 3851 receive four signals. The third flip-flops386_0 and 386_1 receive signals output from the second multiplexers385_0 to 385_1 and transfer the signals according to a third divisionclock CLK/2 produced by dividing the system clock by 2. The thirdmultiplexer 387 receives signals output from the third flip-flops 386_0and 386_1 and outputs the signals sequentially.

As described above, the serialization unit 380 can serialize signalsoutput from the first to thirty second input/output pads DQ0 to DQ31using the flip-flops 382_0 to 382_7, 384_0 to 384_7, and 3860 and 386_1,and the multiplexers 383_0 to 383_7, 385_0, 385_1, and 387. In addition,according to the number of input/output pads, the structure of theserialization unit 380 can be varied, and the division clocks can bevaried.

In accordance with the present invention, signal input/output channelsof the semiconductor memory apparatus are grouped, and each of thegroups shares a CRD circuit. Therefore, the area of the semiconductormemory apparatus occupied by the CRD circuits can be reduced, and thusthe semiconductor memory apparatus can be highly integrated.

Moreover, in accordance with the present invention, the CDR circuit canbe usefully used in a semiconductor memory apparatus, an electronicdevice, or an electronic system for reducing the number of componentsand power consumption.

While the present invention has been described with respect to thespecific embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

1. A method for recovering clock data, comprising; generating a firstserial signal by combining first signals received through even numberedinput/output pads after detecting phases of the first signals;generating a second serial signal by combining second signals receivedthrough odd numbered input/output pads after detecting phases of thesecond signals; transferring a serialized signal produced by combiningthe first and second serial signals; and adjusting output times of newsignals based on a signal transmission state detected using theserialized signal.
 2. The method as recited in claim 1, wherein thegenerating of the first serial signal comprises: receiving first signalstransferred through the even numbered input/output pads; transferringthe first signals according to a receiving reference clock; detectingphases of the first signals; and generating a first serial signal bycombining the first signals.
 3. The method as recited in claim 1,wherein the adjusting of the output times of the new signals comprises:receiving the serialized signal; determining a delay value afterdetecting a signal transmission state by analyzing the serializedsignal; delaying output of new signals according to the determined delayvalue; and outputting the delayed new signals.